Durability of photographic and near photographic images has become a feature that is growing in demand in recent years. Current commercial means of improving durability include lamination with a clear adhesive liquid laminate material or coating (via spray or liquid application) that dries to a clear protective layer. Another lamination process known as “peel apart” lamination has been demonstrated for diffusion transfer images.
The focus of this particular invention is the laminate cartridge used in the peel-apart or thermal transfer lamination process. This technique transfers an overcoat material from a laminate carrying substrate donor support to a printed image. This transfer is often done through a process in which the donor support with the overcoat and the printed media are brought together mechanically with pressure and then heat is applied for a specific exposure time period. This process causes the overcoat material to transfer from the donor to the printed image, the donor can then be peeled away.
One example of this technique uses a heated fuser and a platen to sandwich or press the donor support with overcoat and the printed media together in a mechanical nip. The donor support with overcoat and the printed media are then transported at a constant rate of speed between the heated fuser and the platen such that the exposure time and temperature are controlled. While in the nip, the thermal energy from the heated fuser causes the transfer to take place. The composite laminate carrying substrate donor support, overcoat, and printed media are then transported and manipulated to separate the donor support to be separated from the printed media and its new overcoat layer.
The donor support and the overcoated printed media cannot be easily separated directly upon exiting the nip of the heated fuser and platen. This is usually due to the fact that the overcoat material is in a phase state that does not allow it to have an adhesion affinity for the printed media that is greater than its affinity for the donor support. Therefore, a curing time must be allowed and a separation or peeling process must occur downstream of the nip. This separation or peeling mechanism is usually designed to maximize the following functional requirements:
a) The overcoat remains uniformly applied to the printed media.
b) No contamination is generated in the form of bits of unused or non-adhered overcoat.
c) No donor support or media transport jams are generated.
d) The process works over a wide range of printed media sizes and types, donor support and overcoat material types, and equipment settings.
Mechanisms designed to meet these requirements can be found in a multitude of patents and in practice. For example, in U.S. Pat. No. 5,658,416, MacCollum et al. describes in a method and apparatus that uses a number of means for performing a peel of a laminate from another substrate. The basic mechanism is one in which the separation of substrates is done using a vacuum in conjunction with a peel angle. In addition, a beater blade is used near the separation point to aid the separation by introducing pulsating forces to the substrates. In U.S. Pat. No. 5,643,392, Clough describes in a method in which tension control and a peel angle are used to separate substrates. Schulte, Goodwin et al., and Mistyrik in U.S. Pat. Nos. 5,820,277, 5,788,384, and 6,053,648 discuss other tension control means, respectively. Mistryrik describes a bowed plate for improved transport performance of the substrates. Miyashita in U.S. Pat. No. 4,420,152 in which pawls are used to separate the substrates describes another means. Finally, Pickering et al. describes in U.S. Pat. No. 5,499,880 a donor guide that has a similar function to the peel bar already described.
An example of the process in practice can be found in the Kodak Picture Maker. The Kodak Picture Maker is a commercial printer that uses a thermal dye diffusion to transfer both dye and a protective overcoat to printed media. Specifically, this printing process is one in which dye is transferred from a donor ribbon to media by means of heating a thermal print head (instead of a fuser) while the print head, donor ribbon and media are in mechanical contact. By performing this process in a serial fashion for three separate primary color patches (sometimes there is a fourth black patch) in a controlled manner, an image can be produced on the media. To ensure durability, this printing process is performed one more time except that instead of dye transfer, a continuous clear overcoat material is transferred to the media. The mechanism used to separate the donor support from the overcoated printed media is a peel bar. It is located downstream of the nip and is simply a mechanical feature that is used to define the geometric line along which the donor support is directed to a take-up roll and the overcoated printed media is directed toward the exit of the printer. The distance between the nip and the peel bar is critical in that it provides the curing time required to perform a clean peeling action.
In the above cases, the laminate carrying substrate donor device is used to supply the laminate carrying substrate to the overcoat application apparatus. These devices can be expensive, and difficult to put and keep in position. In addition the prior art devices are not ergometrically efficient causing lost hours and additional costs due to injury or downtime. Finally many of these devices cause machine failures leading to expensive machine downtime and repairs.
Therefore there is a need for an improved laminate-carrying device that is low cost and effective for a wide range of printing processes and peel-apart materials. The intention of the invention is to describe a mechanism that meets these needs.